From the Marine Biological Laboratory, Wood's Hole, and the Laboratory of Physiological Zoology, 

 University of Pennsylvania 



MOMENTARY ELEVATION OF TEMPERATURE AS 

 A MEANS OF PRODUCING ARTIFICIAL PARTHE- 

 NOGENESIS IN STARFISH EGGS AND THE CON- 

 DITIONS OF ITS ACTION 



HY 

 RALPH S. LILLIE 



I INTRODUCTION 



Exposure of mature eggs of Asterias forbesii to the influence of 

 cold sea-water (about 4° to 7°) for somewhat prolonged periods 

 (i to 7 hours) was first shown by Greeley,^ at Wood's Hole in 1901, 

 to be followed by cleavage and production of larvae on return 

 to normal temperatures. Greeley also experimented with tem- 

 peratures higher than the normal, exposing eggs (taken from the 

 same dishes as those used for experiments with cold) to tempera- 

 tures of 31° to 37° for similar periods of time (i to 7 hours); but 

 the results of this treatment were purely negative, the eggs merely 

 absorbing water and undergoing a change which he described as 

 liquefaction. He concluded, somewhat sweepingly, that "seg- 

 mentation of the starfish egg cannot be produced by raising the 

 temperature of the sea-water." He found later (summer of 1902) 

 that temperature was an important factor in the production of 

 parthenogenesis by hypertonic solutions,^ the time of exposure 

 decreasing (within a certain range of temperatures) as the tempera- 

 ture rose, a result confirmed by Lyon^ at Naples in the fall of 

 1902 for species of Strongylocentrotus and Arbacia. But eleva- 

 tion of temperature alone, unaccompanied by other treatment, 

 remained ineffective; moreover, "at 30° it was found impossible 

 to produce artificial parthenogenesis in Asterias or Arbacia with 

 any of the solutions used." In the earlier paper Greeley had 



^ Greeley: American Journal of Physiology, vi, p. 296, 1902. ' 



2 Greeley: Biological Bulletin, iv, p. 129, 1903. 



3 Lyon: American Journal of Physiology, ix, p. 308, 1903. 



The Journal of Experimental Zoology, vol. v, no. 3 



